Spinal fixation procedures are utilized to align and/or fix desired relationships between adjacent vertebral bodies. Such procedures typically include positioning a plurality of spinal fixation assemblies within target vertebrae. These assemblies usually include a threaded shank portion configured to be disposed (e.g., threaded) within a vertebra and a proximal receiving head configured to receive and secure some type of spinal stabilization element (e.g., a rigid rod, a cable, a biological construct, etc.). Once these assemblies are disposed within the desired vertebrae, the spinal stabilization rod can be positioned and secured within the receiving heads thereby allowing the rod to extend along a length of the patient's spinal column. Once secured as such, the installed spinal stabilization rod can hold the vertebrae in the desired spatial relationship, either until desired healing or spinal fusion has taken place, or for some longer period of time.
Due to the intricacies of working in the proximity of the spinal column, such procedures can result in serious patient injury and/or in significant patient trauma. For example, such procedures typically require the spinal fixation assemblies to be delivered directly (i.e., substantially perpendicular to the midline of the patient's spinal column) into a lateral mass of a target vertebra. In light of this trajectory, significant amounts of muscle and tissue must be stripped from the treatment site due to the relatively large distance between the lateral mass entry point and the midline of the spinal column. Also, any slight miscalculation in the delivery trajectory can result in penetration of a distal portion of the assembly (e.g., a pointed tip) into the spinal canal thereby causing significant patient injury. As a further disadvantage, the limited bone mass and/or bone density typically found in the lateral mass portion of a vertebra significantly limits the amount of area available for contacting the fixation assembly thereby hindering the ability to effectively position the fixation assembly within the vertebra.
Thus, there remains a need for methods and systems capable of securely positioning fixation assemblies within target vertebrae while also minimizing the risk of injury and associated patient trauma.